But there is an initial thought of mine. In the Lunar Siyuz-thread I made use of a number that indicated that the earthian gravity decelartes the initial velocity of vehicle flying to the Moon from more than 10 km/s down to 0.9km/s at the distance of 340,000 km to 350,000 km from Earth. Sine the Moonâ€™s gravity is pulling the vehicle I suppose that the deceleration would have been even larger if it wouldnâ€™t have been the direction to the Moon. This mean that the vehicle would have to be accelerated to a velocity significantly above 11 km/s if ist detsination is Mars. This would require more propellant and thus higher costs.

The Moon on the other hand has an escape velocity much less than the earthian one â€“ 2.36 km/s. So if the vehicle would be accelerated by the same amount when launching off the lunar orbit the decleration by the lunar gravity would be much less than at a launch off the earthian orbit. Even the combined gravitation of Moon and Earth in one line should be less since the Moon is so far away from Earth.

It would be interesting to consider both these alternatives.

Perhaps using Earth for a swing-by after a launch out of the lunar orbit would be interesting but at presnet I would prefer to leave that away.

The reason I have in mind regarding the launch off the lunar orbit are the lower trnsportation costs for propellant. The vehicle could fly to the Moon with propellant just sufficient to leave the earthian orbit and to enter a lunar orbit. There it would be refueled and then leave for Mars. Then the costs for tranportation of propellant from the earthian surface into the earthian orbit partially would be replaced by the lower costs for tranporting propellant from the lunar surface into the lunar orbit.

Calculations could make use of the data about Trans Lunar Injection, Trans Earth Injection and Lunar Orbital Insertion. It could be assumed that the Trans Lunar Injection burn occurs at the Moon to launch the vehicle for Mars. Frim Trans Lunar Injection also the Martian Orbital Insertian and the martian Trans Earth Injection could be derived by calculating down linearly. Lunar Orbital Insertion might be used to calculate the return. Whatâ€™s left is the flightfrom Earth to Moon and back later.

If the vehicle would leave the lunar orbit for Mars at the same velocity as it would leave the earthian orbit for Mars then it wouldnâ€™t be decelerated that much as it would by the earthian gravity â€“ and the time to Mars would be shorter. This would have an impact on those costs not considered up to now.

In this post the vehicle not neccesaryly carries humans or living beings â€“ it might carry non-living cargo.